Bearing metal and method of making same



Patented Feb. 4, 1930 UNITED STATES PATENT OFFICE.

ROBERT JAY SHOEMAKER, OF CHICAGO, ILLINOIS, ASSIGNOB TO S. & T. METAL COM- I PANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS BEARING METAL AND METHOD OF MAKING SAME No Drawing. Application filed April 29,

My invention relates to lead alloys and the object of the invention is to provide a hardened,.toughened and stable alloy of lead suitable for bearings, bushings or other elements where anti-friction properties are required or where, for other reasons, a hardened and toughened lead is required.

A further object isto-provide a lead alloy which will not dross when melted.

A further object is to provide a lead alloy which will-not corrode when subject to moist atmosphere.

A further object is to provide an alloy of this character which because of the character of its ingredients and its method of manufacture can be made very cheaply.

This application is a continuation in part of "my copending application filed June 1, b

1925, Serial No. 34,172.

The following will serve to illustrate the principles governing the compounding of the alloy of the present invention. Modifications will be suggested and these modifications and all embodiments of the invention within the scope of the appended claims are intended to be covered by the patent.

The alloy consists of lead, sodium, calcium, aluminum, together with tin which is optional.

In this alloy the primary hardening agent is the sodium. Iii the sodium is used in amounts greater than 0.6% the hardness will increase but also the brittleness of the alloy which may make it undersirable for some uses. The anti-friction qualities, however, are not impaired, but rather improved by increasing the sodium content. The main difficulty in increasing the quantity of sodium used is that the alloy will have an increased tendency to dress when melted, for example,

in casting the hearings or other articles for which the alloy is used, and will have an in.- creased tendency to corrode when in contact with moisture. \Vhile the sodium may be used in any amount up to 1.0% the safe and practical upper limit is probably about 0.8% and with this quantity of sodium, the other ingredients remaining the same as 1927. Serial No. 187,702.

calcium also acts to some extent as a hardener for the lead. There will be a certain loss of calcium due to oxidation in melting and remelting and the amount used should depend to some extent upon this loss. As the amount of calcium used is increased, the hardness and brittleness of the alloy is increased. The calcium, if used in excess, also increases viscosity when the metal is in the molten state, which necessitates a higher pouring temperature. Apparently the calclum and the lead combine and the resultant compound crystallizes out at about 700 F. This reaction etween calcium and lead probably takes place even when small amounts of calcium are formed, but under these circumstances the reaction is on a small scale and may be regarded as practically negligible. The calcium can be used in even smaller amounts than 0.1% but this involves a very careful handling of the metals in process. Otherwisethe sodium will dross out when the alloy is melted.

The aluminum. if used in larger quantities than above specified, will produce no beneficial effect and no effect at all except that as it will notgo into solution in quantities above 0.1% its presence in excess of that amount tends to make the metal viscous.

The tin ingredient, which is optional, may beincreased very considerably, for example up to 5% or possibly 10%, but tin is also a hardener, in the compound specified, so that as the tin content is increased the resultant alloy becomes increasingly hard and increasingly brittle. The preferred limits of the tin are from 1.0% to 5.0%. A compound with the ingredients, except tin, in the proportions as above stated but with the tin 9 forming 5% of the compound, Wlll have a As an example, the ingredients may be in the following proportions:

Sodium, preferably 0.7% or less but not in excess of 1.0

5 Calcium 0.1 to 0.25%

Aluminum 0.02% to 0.1 Lead to make up 100% By using a low sodium content as suggested above, ,0.7 or lower, with the other ingredients in the proportions as given in the example last mentioned an alloy is produced useful for cable coverings and the like.

The method of compounding the alloy is as follows: The lead is heated to a temperature of approximately 1600 Fahrenheit, that is, so as to raise its temperature somewhat above the melting temperature of calcium, which is 1490 Fahrenheit. The melted lead is covered with a supernatant covering which will not burn at this temperature and which will exclude oxygen and be neutral to the metals to be introduced. The preferred covering consists of calcium chloride. The calcium, aluminum and tin, if tin is used, are introduced into the molten lead under its covering of calcium chloride. The melt is then cooled to a temperature of between 650 to 700 F. and the sodium introduced into the melt. A preferable way, however, is to pour the mixture of lead, calcium, aluminum and tin into molds and allow it to cool and then remelt to temperature of 650 to 750 Fahrenheit and add r the sodium. In this case the remelted lead should have a supernatant covering consisting of sodium hydrate (the hydrate of an other alkali metal, as potassium, might be used) and rosin, or soap, fuel-oil or other organic substance which will exclude oxygen. The final mixture is then poured into ingots.

I claim:

1. An alloy consisting principally of lead and containing sodium in an amount not in 46 excess of 1.0% by weight; calcium 0.1% to 0.25%; and aluminum 0.02% to0.1%.

2. An alloy consisting principally of lead and containing tin in an amount from 1.0% to 5.0% by weight; sodium not in excess of 50 1.0% calcium 0.1% to 0.25% and aluminum 0.02% to 0.1%. I '3. An alloy consisting principally of lead and containing sodium not in excess of 0.7% by weight; calcium 0.1% to 0.25% and aluminum 0.02% to 0.1%.

ROBERT JAY SHOEMAKER. 

